Effects of Prenatal Cocaine Exposure on Reversal Learning on Monkeys

Research has demonstrated that prenatal cocaine exposure impairs the ability to adapt to changes in reinforcement. This study attempted to test the generalizability of these findings. The subjects were eight rhesus monkeys divided into four groups that differed in dose of cocaine administered during gestation. At the start of the study, all animals performed a Delayed Matching-to-Sample task. For this task, subjects were presented with one of seven visual stimuli. Pressing the stimulus initiated one of six delays, after which the animals were required to match the stimulus from three available choice stimuli. After eight years, the animals performed a reversal task that required them to select a stimulus that did not match the sample stimulus. Prenatal exposure to cocaine did not significantly affect the ability of the monkeys to perform this reversal. The lack of significance is likely due to unique aspects of the reversal procedure that was used.